Radio relaying



XR. 2,298,435 Examin H. TUNICK RADIO RELAYING Filed Nov. 26, 1940 RAD/0 c'mcu/r AND AMPL lF/EB J TEMP/Q0/VE j' LINE 3 Sheets-Sheet 1 56 FIG.

m EFT/ONE CENTRAL CENTRAL 6724770 STAT/01V ami z RAM 19E NRA NSM/T RECEIVE 1 i 4 5 Run/M SHORT-WAVE TRANSMITTER o/e RECE/VER CENTRAL mar/01v 0R TRANSMITTER CENTRAL CENTRAL spar/01v s' mr/ou" I (/1. TRA' SHORT W4 VE AMPL IF/E/Q ULTRA SHORT-WAVE INVENTQR HARRY TU/V/CK ATTORNEY v Examiner 10- ICLLUISAVHY,

H vQEQY ATTORNEY j :paratus and/or transformerapparatus 48. this event, the ultra short waves may be relayed antenna. I4.

This is a continuation in part of my applicaures 1, 2, 3 and 4 herein correspond, respectively, to Figures 10, 11, 12 and'13 of my parent I case Serial No. 274,744. Figure herein corresponds to Figure 24 of my applicationSerial No. f

310,495, filed December 22, 1939.

frequency signaling systems. It has, as its main object, to provide improved arrangements for relaying signals from one point to another. Other objects, advantages and features of my invention willbe apparent as the more specific description thereof proceeds.

, In the relay system of Figure l the television I pickup camera and video amplifier 40 is emplayed to modulate ultra short wave length transmitting apparatus 42. Numerals 40 and 42 also may diagrammatically indicate the sound pick-up device and sound transmitter. The output of the transmitters 42 of ultra short wave lengths modulated by sound and video signals arecoupled to the open two wire transmission line 44 of a present-day telephone system. Near the coupling point of the transmitting apparatus 42 1s provided a small condenser or other suitable impedance 46 which is of very low value for the ultra short waves appearing at the output of 42',- but which is of high impedance for the telephone currents in line 44.

down to a break in the line represented by the central station 48 or, for example; amplifier apabout the central station 48-by provision of a condenser 50 similar to condenser 46 and by 1 coupling the high frequency-pick-up loop 52 to the line 44 adjacent condenser 50.

' picked up is fed into an amplifier 54 and radi- The energy ated from antenna 56 to a pick-up antenna 58 jeeding amplifier 60. The output of ultra short wave length amplifier 60 is coupled by loop 62 into the 'open two wire telephone line 64 where it is again transmitted along the open wire lines to the next central station or break in the telephone line represented by rectangle 66. Here again, a condenser or impedance 68 is connected across the line 64 and loop I0 is coupled thereto,

feeding an amplifier 12 which may feed a nondirective ultra short wave length broadcasting In the system shown in Figure 1, the telephone line sections 44, 64 may be a mile or several miles in length, for it will be found that for radio i'e- The telephone line @44 wil1 then carry these ultra short wave lengths RADIO RELAYING 'Ha'rry Tunick, Rye, N. Y., assignor to Radio-Corppration of America, a corporation of Dela- I fnpplication November 26, 1940, Serial'No'.367, 185- I I.

' zclei'ms. (Cl.g50-15) f i "min Serial No. 274,744, filed May 20, .1939. -Fig-- I My present invention relates to improved high laying purposes, the attenuation and frequency discrimination of suchopen wire lines will not be found too objectionable. The waves so relayed in the system shown in Figure 1 or, for that matter, in any of the figures described in this application may be amplitude modulated, frequency modulated or phase modulated waves.

Other ways of coupling into the ordinary two wire commercial telephone line are illustrated in Figures 2 and 3. In Figure 2, the two wire 3 transmission line is shunted by an impedance dipole antenna 92.

45,-as described in connection with Figure 1. Across the two wire line 80 there is connected a short transmission line connected to the Antenna 92 picks up energy radiated by the radiating antenna 94, in turn connected to the ultra short wave length trans- I mitter 85, the wave-energy traveling down the telephone line 80 to a point such as represented by central station 48 of Figure l, at which point the radio relay circuit 52, 54, 56, 58, 60, 62 is duplicated-as in Figure l, but for the sake of simplicity is not repeated'in connection with Figure 2. v

- In Figure 3, the open wire telephone line I00, consisting of two wires mounted, as is common practice, upon telephone poles, runs from central station I02 to station I04 and then continues in line I06. The ultra short wave lengthtransmitter is illustrated at point I08 and feeds into line H0 by way of coupling loops II 2. The line H0 is connected between the condensers H4, serially connected across the transmission line I00, the two condensers H4 being of low impedance for ultra short waves fed through loops I I2, but. of relatively high impedance for normal tele-' phone currents carried by line I00. The ultra short waves travel towards the right down two wire line I00 and passingthrough condensers H6 similar to condensers H4 are amplified by amplifier H8 and radiated over antenna I20 to ee ENT the receiving antenna I22. At the receiving point I22, the ultra short waves are further amplified in amplifier I24 and fed again through condensers I26, similar in construction and common to condensers H4, to excite the wires I 06 of the open two wire telephone line in parallel for ultra short wave transmission. At any point along the line transmitters, such as H8, may indicate a non-directional broadcasting transmitter in addition to indicating a relay transmitter. Also, it

a should be obvious that the system may be carried out with transmission from right towards the left, rather than as explained from left to wards the right.

eti

nels may be reversed, the video signals being transmitted on the telephone line and the audio being relayed partly by wire and partly by air. The television pick-up camera 300 feeds amplifying apparatus and ultra short wave transmitter 302 in turn excites the transmitting antenna 304. From what has gone on before, it should be clear that these signals are picked up and relayed jthrough relays 303 and 308 to the terminal station 340 whose amplifier 3l2 may feed a broad-.

' cast'television antenna 3l4 of the-type described by N- E. Lindenblad in his application Serial No. 208,573, filed May 18, 1938. The relay stations 303 and 308 may be constructed as described in connection with Figures 1 through 7 for example of my copending application Serial No. 274,744, filed May 20, 1939. The type of a modulation employed for the television channel I may be of the amplitude modulation type.

The audio pick-up microphone 3 l6, which may also represent the audio amplifier, is arranged I ".Qto modulate the ultra short wave transmitter 3l8, operating on a different frequency than that employed in the television channel. Furthermore, the transmitter 3l8 may be amplitude modulated, but is preferably frequency modulated and the ultra short wave length frequency modulated waves are fed along the telephone transmission lines 320, radio relay 322 and transmission line 324 as'described in connection with Figures 1, 2 and 3, rectangles 32B, 328, 330 indi- -cating telephone sub-stations. The frequency modulated ultra short waves at station 330 are fed through loop 334 and line 33 6 to a receiving amplifier 338, in turn-feeding an audio broad casting antenna 340.

- For reception of the sound channel at ornear station 330, as for exampl for monitoring pur poses, the pick-up loop 342 is provided which :may be switched into transmission line 344 into the frequency modulated ultra short wave length receiver 346. The output of this receiver may be heard in the telephones 348 which may, of course, be a loudspeaker.

On the other hand, if it is desired to employ an ordinary broadcasting set for hearing the frequency modulated ultra short wave audio signals, the audio output of the ultra short wave receiver 346 may be fed through transmission I line 350 to 'modulate a broadcast wave length or long wave length oscillator 352. The modulated output of this oscillator may then be fed I directly as indicated by lines 344 r radiated into the ordinary broadcast receiver 356 provided with loudspeaker 358. The receiver 356 should. of course, when employed, as described, be tuned so as to receive the long wave generated at 352. Similarly, this ultra short wave length system may be switched to a pick-up antenna 360 at points 362 rather than to the loop 342, in which case the ultra short wave length signals picked up on antenna 360 will be reproduced either by the ultra short wave length receiver 346 or, as adapted by way of the modulated oscillator 35!, will be heard in the loudspeaker 358.

The system described in Figure 4 offers certain advantages in that if desired the audio channel may be operated at relatively low power. 8 it should be understood that when frequency -modulation is referred to herein, frel y deviations less than, equal to or several audio and video channels will be of the frequency 1 modulated type. Or, if desired, the video relay channel may carry frequency modulated waves and the audio channel may carry amplitude modulated waves.

In Figure 1, ultra short wave television and mounted in a truck and coupled to the comliiisleee F? limina s r. ire 44. Similarly,'"'in Figure Z, 93 may represen m 4 a jr nobile.,truck carrying a television and sound ultra shortwave transmitting apparatus feeding Iin'e'80 through the mediumofhtheradio I circuit including antennas94 and 92.

It should'be clearly understood that in the systems such as shown in Figure 4, the oscillation prevention means, such as illustrated in Figures 1 through 7 inclusive of my copending application Serial No. 274,744, filed May 20, 1939, may be employed. For example, in Figure 4 the oscillation generating prevention means of Figures 1 through 7 inclusive of my parent application may be employed at any one of the relay stations 306, 308, etc. and may also be employed at the terminal station 310. The

schemes of preventing feed-back and sustained oscillation generation may also be applied to the combined wire line and radio links. For example, referring to Figure 4 herein, the system of Figure 5 of my parent application may .be employed at station 338, the only difference then existing will be that the receiving antenna RA of Figure 5 will be replaced by the loop 334 of Figure 4 herein. Also, for example, in Figure 1- any of the oscillation prevention systems of Figures 1 through 7 of my parent application Serial No. 274,744 may be employed, in which case the loops 52, 62 take the place of the receiving and transmitting antennas, respectively, of Figures 1 through 7 of my parent case Serial No. 274,744.

Referring again to Figure 4, it is preferred that the television broadcast antenna be fed with amplitude modulated waves from the amplifier or transmitter 3|2. Also, it is preferred that the corresponding audio system employing antenna 340 be fed with frequency modulated waves, having relatively wide deviations, from the amplifier or ultra short wave transmitter 338.

However, it should also be clearly understood that my invention contemplates the employment of wide frequency modulation for the television or video channel, in which case the carrier frequency may be swung in frequency an absolute amount several times the highest video modulation frequency away from the carrier means frequency for the largest amplitude of the video modulation currents or voltages. For all other video signal strengths, the carrier may be swung the arrangement of Figure 2; The next line seetion may be fed either in push-pull or in parallel as desired, etc.

In the system of Figure 5, which corresponds to Figure 24 of my copending application Serial No. 310,495, filed December 22, 1939, the pick-up unit 3000, which may be a voice, television or facsimile pick-up unit, frequency or phase modulates a sub-carrier generated by apparatus within rectanglev 3002. This frequency or phase modulated sub-carrier is fed over land lines 3004 to a suitable frequency or phase modulation receiver 3006 which reproduces'currents of modulation frequency similar to those fed from 3000 into the sub-carrier system 3002. The output of frequency or phase modulation receiver 3006 is then used to frequency or phase modulate the radio transmitter 3008 whose output is in turn radiated by radiator 30 I 0.

The transmitted frequency modulated waves are received on the receiving antenna 3012 and translated by the frequency or phase modulated receiver 3014 into the modulation frequency waves corresponding to those at the output of apparatus 3000 at the transmitter. These demodulated waves of modulation frequency are used to frequency or phase modulate a sub-carrier wave in the apparatus represented by 3016.

This frequency or phase modulated sub-carrier I g is then fed over land line 3018 to a distant receiving point at which a frequency or phase modulation receiver 3020 is located. The receiver 3020 ole-modulates the frequency or phase modulated sub-carrier and feeds the de-modulated waves into a loudspeaker facsimile recorder or television reproducing apparatus 3022.

The foregoing system has among its advantages the fact that the pick-up unit 3000 may be remotely located from the transmitting antenna 3010 and that the de-modulating receiver 3006 may be used both for monitoring as well as for modulating the radio transmitter 3008. Similarly. the receiving arrangement is advantageous since the receiving antenna 3012 may be located in the suburbs of a city and the reproducing apparatus 3022 may be located within a city, in which event the urban noises generated in urban areas are kept from affecting the output of 3022.

Any of the transmitters or receivers specifically described in my copending application Serial No. 310,495, filed December 22, 1939, and in my copending application Serial No. 361,413, filed October 16, 1940, may be used herein for the transmitters and receivers represented by rectangles.

Having thus described my invention, what I claim is: I

1. A short wave relay system comprising a relatively long two wire transmission line, apparatus offering relatively high impedance to short waves connected in said line intermediate the ends thereof, an impedance having a, low impedance value to short waves and high impedance value to long waves connected across one end of said line, a source Of short waves, a circuit coupling said source to said line adjacent said impedance having low value to short waves and high value to long waves whereby short waves travel down said line to one side of said apparatus havin high impedance connected in said line, a pickup device picking up short waves from said line at said one side of said apparatus, an amplifier amplifying the picked up waves, a directive antenna system for directively transmitting said amplified short waves around said apparatus, and a circuit for feeding said directively transmitted short waves into said line at the other side of said apparatus for further transmission of said short waves down said line away from said apparatus. a

2. Apparatus as claimed in claim 1 characterized by the factv that condensers are connected across said two wire line at each of said coupling points, said condensers having low impedance for short waves and relatively high re'actance for long waves.

HARRY TUNICK. 

